39
4.22
1959 samples.
Specimens too large for convenient
storage and air transport were dissected in the field.
Selected tissues were stored,
frozen,
in polyethylene bags.
Smaller specimens were stored whole in polyethylene bags and
frozen.
Chemical preservatives were avoided because of the
possibility of trace element contamination.
shipped,
frozen,
dissected.
samples,
to the
The samples were
Seattle laboratory where they were
In addition to the tissues taken from the 1958
the eyes were taken from the summer,
Tissue samples,
1959 collection.
generally of not more than 5 grams,
from indi-
vidual fish were kept separate in pyrex beakers, air dried at
90° c., and ashed by a method suggested by Sandell (1959):
(1)
To the dried sample in a pyrex beaker, enough 70
per cent or 90 per cant nitric acid was added
dropwise to wet the sample thoroughly and then
heated gently to dryness on a warm hot plate,
(2)
The sample was then inserted into a muffle furnace
at 500° Cc. for one hour.
(3)
If the sample was not completely converted to ash,
the procedure was repeated,
adding a few drops of
H202 at the end of the first step.